» Sea levels could rise by up to one-and-a-half meters by end of 21st century

Sea levels could rise by up to one-and-a-half meters by end of 21st century

Published: Wednesday, April 16, 2008, 13:02 [IST]

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London, April 16 : A new scientific analysis has suggested that sea levels could rise by up to one-and-a-half meters by the end of this century.

According to a report by BBC news, the new analysis comes from a UK/Finnish team, which has built a computer model linking temperatures to sea levels for the last two millennia.

It suggests that last year; IPCC's forecast of an average rise in global sea levels of 28-43cm by 2100 is too conservative.

A major reason for this underestimation is that the IPCC was unable to include the contribution from "accelerated" melting of polar ice sheets as water temperatures warm because the processes involved were not yet understood.

According to Svetlana Jevrejeva from the Proudman Oceanographic Laboratory (POL) near Liverpool, UK, for the past 2,000 years, the global average sea level was very stable, it only varied by about 20 cm.

"But by the end of the century, we predict it will rise by between 0.8m and 1.5m," she said. "The rapid rise in the coming years is associated with the rapid melting of ice sheets," she added.

For their analysis, the researchers created a model, which is able to accurately mimic sea levels reliably observed by tide gauges over the last 300 years.

"There is little concrete evidence on sea levels for the thousands of years before that," explained POL's Simon Holgate.

"Against that, the currently observed rise of about three mm per year is significant, and many scientists working in the field expect to see an acceleration," he said.

The latest satellite data indicates that the Greenland and West Antarctic ice sheets are losing mass, though the much bigger East Antarctic sheet may be gaining mass.

A full melting of Greenland and West Antarctica would raise sea levels by many metres; but the process, if it happened, would take centuries.

"There's a lot of evidence out there that we're going to see at least a metre of sea level rise by 2100," said Steve Nerem from the University of Colorado.

According to Nerem, "We're seeing big changes in Greenland and West Antarctica, so we're expecting this to show up in the sea level data as an increase in the rate we've been observing."

However, a rise of even a metre could have major implications for low-lying countries such as Bangladesh, whose economies are not geared up to build sophisticated sea defence systems.

"Eighty to 90% of Bangladesh is within a metre or so of sea level," said Dr Holgate. "So, if you live in the Ganges delta, you're in a lot of trouble; and that's an awful lot of people," he added.